Compressor Air Line Freezing

Compressor Air Line Freezing
(Last Updated On: August 3, 2020)

We’ve discussed many times how compressing air generates free water and water vapor in the compressor tank and in the air lines. What happens if a line goes outside?

If your air compressor is in the sub tropics or tropics….nothing special.

If you happen to be in northern latitudes however, there’s a real likelihood that the water that’s getting into your air lines, where those air lines exit a warm building to travel to another through exposed winter time temperatures, will freeze. Get enough of it in the lines, and it will freeze solid and block your air line.

Compressor Air Line Freezing up

Sometimes you cannot help but have an air line go outside to get to another location, and if you are one of the unfortunate folks that lives where the air freezes, here’s what you can do.

First choice…run a heater wire the exposed length of the air line, and then insulate it so that the temperature in the line doesn’t get below freezing. Be prepared to have a lot of water traveling along that line, so have a drop leg with an auto drain where the line re-enters a warm building.

Next choice…reduce the dew point of the compressed air just before it leaves the warm building¬† so that the dew point of the air entering the cold line outside is well below the lowest temperature that the compressed air might experience as it traverses the outside air line. If the air is dry enough, there won’t be any water in the air to freeze, and you won’t have a problem.¬† Warning, this is an expensive and maintenance prone solution.

Last…don’t do it! Determine the requirements of compressed air in the building to which the exposed air line was traveling, and install a compressor there to supply that part of your operation.

Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.


  1. a do you have to have a 90 gallon to 100 gallon air compressor to sand blast with a 200 pound sandblaster but whats the difrent betwen gallons and psi so it if you have 90 psi -100 psi

  2. Is it possible to supply Compressed Air at -8 / -10oC to cool a mould in a manufacturing process.At present the Process is using a ‘Meech Airtech’ Cold Stream Gun to cool the air coming from the Compressor.

    • Tom, I’m sure that the technology exists to cool your compressed air supply to whatever temperature you want. In order for the air to be brought down to that temperature level though, it would have to be extremely dry, as any water vapour would condense out and freeze up things.

      How about it, readers? Got any sources of super cool compressed air for Tom?


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